This invention pertains to methods and apparatus for applying orthodontic brackets to teeth.
One of the more difficult problems in applying orthodontic brackets to teeth is how to align the brackets properly with the teeth. This problem arises in the application of both lingual and labial brackets. One method of applying brackets to teeth is known in the art as the "direct" method. This method calls for simply mounting a pre-formed pad carrying a bracket directly to the tooth in the patient's mouth. "Pre-formed" means that the pad has a predetermined, usually oval, small size shape which is not altered during or after positioning the pad and bracket on a tooth. Conventionally, the pad is also substantially rigid.
Another method is the "indirect" method, which provides for pre-positioning a pre-formed pad and bracket on a plaster model of the patient's mouth. The pad is affixed to the plaster teeth with a water soluble glue. A silicone matrix is applied over the model, with the brackets mounted thereon to form a mold over the entire model. After dissolving the water soluble glue, the mold is removed from the model. Bonding cement is then applied to the pads which are exposed inside the matrix, and the entire matrix, including the brackets and pads, is fitted into the mouth. Once the bonding cement is solidified, the matrix is removed, leaving the brackets behind. Because it is so cumbersome and not as accurate as desired, this is not the technique of choice. However, it is commonly used for applying lingual brackets because the direct method is too difficult to use inside the mouth. A variation of the indirect method is applied one tooth at a time. However, the accuracy of bracket placement is still often less than optimal. The indirect techniques also cause bonding cement to be smeared onto portions of the tooth other than beneath the pad, necessitating considerable cleaning after the brackets are applied.
Accordingly, need remains for a better approach to application of orthodontic brackets to teeth.